The present invention relates to a seat back structure.
Seat backs of vehicles generally have a structure in which a cushion member is disposed on a seating surface side of a seat back panel made of metal. Since the seat back panel generally has quite a large area, it is comprised of a metal plate member to secure rigidity. However, the rigidity is insufficient with a simple plate member. JP2011-105049A discloses a seat back panel including a large number of V-shaped bead portions, which are formed vertically adjacent to each other in a seat back, in order to increase the rigidity of the seat back panel.
For a weight reduction of the seat back, an intermediate member is inserted into a space between a seat back panel and a cushion member is considered. For example, it is possible to reduce the weight, by using a member of which a specific gravity is lower than that of the cushion member and a hardness is higher than that of the cushion member to be the intermediate member, compared to a case where a cushion member forms the part corresponding to the intermediate member. Recently, a further reduction in weight is desired.